What is vulcanization and why is it important for rubber
Vulcanization is a chemical process that turns raw rubber into a durable, elastic and heat-resistant rubber. Without this stage, rubber products would be sticky, weak and unstable against temperature changes. It is vulcanization that turns rubber into such a widely used industrial material.
What happens during vulcanization?
Raw rubber consists of long polymer chains that are weakly bonded to one another. During vulcanization, cross-links form between these chains. Usually sulfur atoms play the role of these bridges, chemically bonding the chains together. As a result, the material turns into a single, three-dimensional elastic network.
The role of sulfur
In traditional vulcanization, the main agent is sulfur. The amount of sulfur directly determines the hardness of the final product: little sulfur gives a soft and elastic material, while a lot of sulfur gives a hard one. This ratio is measured by Shore hardness and is precisely controlled in the formulation.
Temperature and time
Vulcanization usually takes place in the range of 140–180 °C. Temperature and holding time (vulcanization time) are very important: undercured material is weak, while overcured material is brittle. Finding this balance is the main task of the process engineer.
The properties vulcanization gives rubber
- Elasticity: the material returns to its original shape after being stretched.
- Strength: tensile and tear resistance increases sharply.
- Heat resistance: it keeps its shape at high temperatures.
- Chemical resistance: resistance to oil, ozone and weather conditions improves.
- Wear resistance: the surface becomes more resistant to abrasion.
The vulcanization stage in manufacturing
Vulcanization is an integral part of all the main production methods. In extrusion the profile is vulcanized in a separate heat channel, while in injection and compression molding the part is vulcanized directly inside the heated mold. In all three cases, the rubber compounds stage is decisive for preparing the correct formulation.
At NUR KAUÇUK, vulcanization parameters are checked in our own laboratory for every batch. This ensures the material meets the project requirements. For detailed information, see the manufacturing and quality sections.
Do you need properly vulcanized, durable rubber products? Review our products and contact us regarding your technical requirements.